Physical activity, a factor in healthy brain aging, is part of multidomain dementia prevention trials. ISTOCK.COM/KALI9 Can diet and exercise lower your risk of dementia? Rigorous clinical trials aim to find out May. 27, 2021 , 1:00 PM For the past 3 years, about 6000 middle-aged and elderly Australians have pumped iron, loaded up on greens and whole grains, strived to quell stress, and challenged their wits with computer exercises, all in an effort to preserve their cognition. They’re part of a clinical trial called Maintain Your Brain, one of about 30 current or planned studies that eschew pharmaceutical interventions and test whether altering multiple aspects of participants’ lives improves brain health. Such multidomain studies may finally reveal whether modifying diet, exercise, and other factors can slow cognitive decline as people age—or even prevent dementia.